Self-baking electrode



C. W. SDERBERG SELF BAKING ELEGTRODE Oct. 2, 1928.

Filed Sept. 18, 1926 Patented Oct. 2, 1928.

UNITED STATES 1,686,414 PATENT oFFlcE.

CARL Wm BDIRBIBG, OIOSLO, NORWAY, ASSIGNOB'TO DET N038 mm- I'OB INDUSTBIOF NORWAY, OF OSLO, N ORWAY. i

SEH-BAXIN ELECTBODE.

Application led september 18, 1986, Serial Io. 138,275, and in NorwaySeptember 19, 1925.

The so-called self-baking electrodes, i. e. electrodes that are bakedwhile iii-use in the electric furnace, ordinarily consist of one bakedand one unbaked part and means will 6 have to be provided for conductinthe electric current to the baked art of: the electrode. A present thisis or inarily made aceording to my U. S. Patent No. 1,440,724 datedJanuary 2nd, 1923, by surrounding l the electrode by a metallic shellstructure consisting of a metal mantle provided with inwardly projectingribs that give a good electrical contact. Both casing and ribs pass intothe furnace as the electrode is consumed l5 and become a part of thecharge. In man instances the presence of this metal, whic on account ofthe high temperature required to properly bake the electrode isgenerally iron', is not objectionable. However, Where the continuousself-baking electrodes are to be used in the'electrolytic production ofaluminum and in similar cases, the addition of iron from the electrodeis very objectionable as it renders the aluminum im ure. For this reasonas much as possible o the shell structure may be made of aluminum, butinasmuch as the aluminum melts at a temperature considerably below thatat which the electrode has attained a reasonably good electricalconductivity, the use of aluminum for the whole shel has met withdifficulty so that the internally projecting ribs are now generally madeof iron or other comparatively diiiicultl fusible metal (U. S. Pat.1,679,284 of Jens estly), which remains solid and conducts the currentto a point far enough down in the electrode so that the voltage lossesin the electrode do not become too large a factor in the power con- 4 40sumption of the furnace. These inwardly projecting ribs, howeveralthough ver thin, introduce an appreciable and un esired amount of ironinto the aluminum produced. The object of the present invention is toprovide a .shell structure for a self-baking electrode, in which themantle-ifany-may be made of an easily fusible metal such as aluminum andthe ribs may be made of a diflicultly fusible metal such as iron, wherethe ribs may be given a. sucient cross-section so that the voltage lossin them is materially reduced as compared with that in the ribspreviously employed, and where the metal in these ribs is notpermittedto enter u the furnace and contaminate the product.

This is accomplished b separatin the ribs from the shell so that t eyare mec anically independent of each other and may be displaced withrelation to each other, especially in a direction parallel to the axisof the electrode. Thereby the ribs are converted into special contactsinserted into or in other ways brought in contact with thebaked part ofthe electrode. If a metallic mantle is used, which encloses and shapesthe electrode, the same may therefore pass into the furnace with it,While. the ribs may be so arranged that they carry a large part of thecurrent to the thoroughly baked lower portion of the electrodes, but arenot permitted to be fed into and consumed in the furnace. Thus themantle may be made of an easily fusible metal, such as aluminum, and theribs of a more diflicultly fusible metal such as iron, withoutcontaminating the furnace jsiroduct with the diiiicultly fusible metal.

ince the invention is of particular importance in the use of thecontinuous self-baking Lelectrode for the roduction of aluminum by theelectrolyses of) its oxide in a molten bath, the example chosen fordescription will refery particularly to such an electrode, although itshould be clearly understood that the lnvention is also applicable toother cases where similar requirements have to be met.

In the attached drawing Fig. 1 shows a horizontal section through anelectrode in which this invention is embodied, andFig. 2 shows anenlarged vertical section along the line a-b of Fig. 1.

In these drawings 1 is electrode mass, 2 is an aluminum mantle which, aswill be seen, is bent inwardly into the electrode mass to give'room forthe ribs 3 and 4, which are of iron. The ribs have an externallyextending portion 5 where the electric cables 6 may be connected.- Asappears from Fig.

r2 the ribs are made of two parts 3 and 4,

ed. The ribs are made so long that they project above the upper end ofthe mantle. Vhen the lower end of the rib approaches the melt, the ribis loosened by a blow on one part of its upper end and the whole rib ispulled upwards a suitable distance. It is thus possible to move one ribat a time and the operation of the furnace may at all times be continuedwithout disturbance. The mantle is made from sections which arepreviously formed and vplaced in the position` shown with reference tothe ribs, andjoined to each other by welding. The tamping of theelectrode mass takes place as is usual with self-baking electrodes andthe electrode may be supported in any known way. The ribs should besuspended from their upper part. The lower end of the ribs will alwaystake the temperature of the electrode at this point, that is about 90()oC. and must therefore be provided with a non-oxidizable coating offerrochromium or the like. To get the best possible cont-act the ribsmay increase in thickness, both towards their lower end where thealuminum mantle melts, and inwardly towards the axis of the electrode.rlhe supply of current may of course take place in the usual mannerthrough the carrying mechanism of the electrode as well as through theribs. If desirable, the mantle may of course be provided withprojections or the like to provide better attachment for the electrodemass.

Obviously the mode of application of the present invention may be variedwithin wide limits and the above example therefore is not intended tolimit the invention.

Claims:

1. The combination of an electrode baked while in use in the electricfurnace, an electrode holder, and a current-carrying contact movablerelatively to the electrode and the electrode holder.

2. The combination with an electrode baked while in use in the electricfurnace, of a metallic current-carrying contact extending into theelectrode beyond the periphery thereof and movable relatively to theelect-rode.

3. The combination with an elect-rode baked while in use in the electricfurnace, of a plurality of current-carrying contacts extending into theelectrode beyond the periphery thereof, such contacts being movablerelative to each other.

4. The combination with an electrode baked while in use in the electricfurnace, of a current-carrying Contact extending into the electrodebeyond the periphery thereof, such contact comprising parts relativelydisplaceable with respect to each other, and adapted when so displacedto engage the electrode to make contact therewith.

5. The combination with an electrode baked while in use in the electricfurnace,

of a current-carryin contact extending into the electrode beyon theperiphery thereof, such contact comprising a plurality of movablewedge-shaped parts.

6. The combination with an electrode baked while in use in the electricfurnace, of a metallic current-carrying contact extending into theelectrode beyond the periphery thereof and movable relatively to theelectrode, the lower portion of such contact being provided with anon-oxidizing coatin 7. The combination with an electr e baked while inuse in the electric furnace, of a current-carryin contact extending intothe electrode beyon the periphery thereof, such contact comprising aplurality of relatively movable parts suspended from their upper ends.

8. The combination with and electrode baked while in use in the electricfurnace, of a current-carrying contact extending into the electrodebeyond the periphery thereof and movable relativel to the electrode, andan electric lead direct y connected with such contact.

9. A metal shell for an electrode baked while in use in the electricfurnace characterized by the fact that it comprises a. plurality ofmechanically distinct parts mov,- able relatively to each other.

10. A metal shell for electrodes baked while in use in the electricfurnace comprising a mantle containing the electrode mass, and ribsdisplaceable with respect to the mantle.

11. A metal shell for electrodes baked while in use in the electricfurnace comprising a mantle containing the electrode mass and ribsdisplaceable with respect to the mantle, the mantle being made of arelatively easily fusible metal and the ribs being made of comparativelydifiiculty fusible metal.

12. A metal shell for electrodes baked while in use in the electricfurnace comprising a mantle containing the electrode mass, and ribsdisplaceable with respect to the mantle, the mantle being made ofaluminum and the ribs being made of iron.

13. A met-al shell for electrodes baked while in use in the electricfurnace, comprising an aluminum mantle containing the electrode mass,anda movable iron rib comprising parts relatively displaceable withrespect to each other and adapted when so displaced to engage theelectrode to make contact therewith.

14. A metal shell for an electrode baked while in use in the electricfurnace comprising' an aluminum mantle, and an iron current-carryingcontact extending into the electrode beyond the periphery thereof, suchcontact comprising a plurality of wedgeshaped parts.

15. A metal shell for an electrode baked while in use` in the electricfurnace. comprislll ing a mantle made of a relatively easily fusiblemetal, and a current-carrying rib of comparatively diculty fusible metalextending into the electrode be ond the pehiphery" thereof, the lowerpart o such rib being provided with a non-oxidizable coating. v 16. Ameta-l shell for an electrode baked while in use in the electric furnacecomprising a mantle of one composition, and a rib movable relatively tothe mantle and made Aof another composition, the rib being suspendedfrom its u per end.

17. A metal shel for an electrode baked while in use in the electricfurnace comprising a mantle of a relatively easily fusible metal andribs displaceable with respect to CARL WILHELM SDERBERG.

